3KXK

Crystal structure of SsGBP mutation variant G235P

Summary for 3KXK

• Entry DOI: 10.2210/pdb3kxk/pdb
• Related: 2QTH 3KXI 3KXL
• Descriptor: GTP-binding protein (HflX) (2 entities in total)
• Functional Keywords: ssgbp, hflx, gtpase, gtp hydrolysis, nucleotide binding protein
• Biological source: Sulfolobus solfataricus
• Cellular location: Cytoplasm : Q980M3
• Total number of polymer chains: 2
• Total formula weight: 83409.31

Authors

Huang, B.,Li, X.,Zhang, X.C.,Rao, Z. (deposition date: 2009-12-03, release date: 2010-05-26, Last modification date: 2023-11-01)

Primary citation

Huang, B.,Wu, H.,Hao, N.,Blombach, F.,van der Oost, J.,Li, X.,Zhang, X.C.,Rao, Z.
Functional study on GTP hydrolysis by the GTP binding protein from Sulfolobus solfataricus, a member of the HflX family.
J.Biochem., 2010

PubMed Abstract: GTPase domains from members of the HflX protein family have their catalytic glutamine residue of the DxxGQ motif substituted by phenylalanine, while they are still able to hydrolyse GTP. This appears to challenge the traditional view of GTP hydrolysis mechanism of Ras-like GTPases. SsGBP from the hyperthermophilic archaeon Sulfolobus solfataricus provided the first crystal structure of the HflX family. Here, we report structure-based mutagenesis analyses on SsGBP. Six-point mutations were individually introduced in the Ras-like GTPase domain including regions of P-loop, switches I and II. Intrinsic GTPase activities and thermal stabilities of these variants together with the wild-type full-length SsGBP and its isolated GTPase domain were analysed. Both functional and structural analyses of G235P and G235S mutants, which showed total and partial loss of the GTP hydrolyzing activity, respectively, support our hypothesis that the role of aligning a nucleophilic water molecule by the Ras Gln60 residue is replaced by the backbone amide group of Gly235 in SsGBP. Together with functional studies of other mutants, we conclude that the classical view of GTP hydrolysis mechanism likely remains the same in the HflX family with a twist in the entity of the nucleophilic alignment.

PubMed: 20400571
DOI: 10.1093/jb/mvq039

Experimental method

X-RAY DIFFRACTION (2.35 Å)